KABUL, Afghanistan -- A team of suicide bombers attacked a compound belonging to Afghanistan's spy agency Wednesday, killing at least one guard and injuring 33 civilians in a brazen strike at the heavily fortified heart of the capital, officials said.
One of the attackers detonated a minivan packed with explosives at the entrance to the National Security Directorate, said agency spokesman Shafiqullah Tahiri.
Five gunmen wearing suicide vests drove up behind him and were killed in an exchange of gunfire with security forces, he told a news conference. Their van was also rigged to explode. Security forces deactivated the device with three minutes left on the timer, Tahiri said.
The Taliban claimed responsibility for the midday attack in a text message sent to journalists.
Sediq Sediqqi, a spokesman for the Interior Ministry, which oversees the police, praised the quick response of Afghan security forces.
"Six suicide bombers were killed within less than 10 minutes, which is itself an assurance to the people of Afghanistan," Sediqqi told reporters. "Their security forces have achieved the ability to eliminate the worst terrorists in the world within minutes."
Some nearby business owners, however, questioned how the two vehicles could have penetrated one of the most heavily guarded districts of Kabul without being detected.
Mohammad Hadi, who owns a stationary store in the same street as the intelligence agency, said this was the second time that an explosion had shattered his windows and damaged his merchandise. His 16-year-old son, Mohammad Zaki, had a bloodied face from flying glass.
It was a huge explosion," Hadi said. "The government should prevent such incidents."
It was the second time the National Security Directorate was targeted in less than two months. In December, agency director Asadullah Khalid was injured in a suicide bombing at a directorate guest house in Kabul. He is receiving treatment in the United States.
Wednesday's attack happened in a heavily trafficked area that also houses the police headquarters, Interior Ministry and several foreign embassies. The blast, which could be heard across central Kabul, left a trail of charred cars and shattered glass.
The attackers used a form of liquid gel explosive that has not been previously seen in Afghanistan, security officials said. Investigators are trying to determine the source.
The bombers were also armed with Kalashnikov assault rifles, grenades and large quantities of bullets, security officials said.
The weapons were later displayed for journalists along with other items recovered from the attackers' vehicle: Afghan and Pakistani banknotes, fake identification cards, ammunition vests, muddy boots, bottled water and the remnants of a burger and fries.
Special correspondent Hashmat Baktash contributed to this report.